Pneumatic hammer



E. w. STEVENS PNEUMATIC HAMMER Filed Oct. 1. 1928 Nov. 17, 1931.

\\\\L- i t INVENTOR.

fdn/ara l/ Sfevews ATTORNEY.

Patented Nov. 17, 1931 UNITED STATES PATENT OFFICE EDWARD W. STEVENS, 0F DETROIT, MICHIGAN, ASSIGNOR TO CHICAGO PNEUMATIC TOOL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY PNEUMATIC HAMMER Application filed October 1, 1928. Serial No. 309,506.

This invention relates to fluid pressure percussive tools; and is particularly concerned with the distribution and control of the pressure fluid for actuating the percussive member or piston.

One object of the invention is to improve the operation of pneumatic percussive tools. Another object is to secure improved results with a reduced consumption of motive fluid. Another object is to eliminate all constant pressure or leak ports which tend to cause premature throwing of the valve and which cause waste of the motive fluid. Other objects will be apparent from the detailed description which follows.

The invention includes the use of an auxiliary valve in addition to the main control valve, the former serving to control a passage by which pressure fluid is admitted from the piston chamber to one of the valve chambers to initiate movement of the main valve in one direction. The same valve chamber provides for the admission of live motive fluid to complete the movement of the valve and to drive the piston on its rearward or non-working stroke. The auxiliary valve prevents loss of any of the live motive fluid which is admitted to the said valve chamber and a novel disposition of the ports in the said valve chamber insures full movement of the main valve.

In order to illustrate the invention one concrete embodiment thereof is shown in the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional view showing certain parts in side elevation;

Fig. 2 is afragmentary sectional view on an enlarged scale of a portion of the hammer shown in Fig. 1 showing the valve beginning its rearward movement;

Fig. Sis a detail sectional view taken at a slightly different angle to show an exhaust passage but with the valve in the same posi-v tion;

Fig. 4 is a view similar to Fig. 2 but with the lower portion sectioned as shown in Fig. 3, the valve being in its rearward position;

Fig. 5 is a diagrammatic disclosure of the interior of the valve case; and

der 7 providing a piston chamber 7 a in which I reciprocates a hammer piston 8 arranged to deliver its blows to a working tool, such as a rivet set 9, retained in the outer end of the cylinder by a rivet set clip 10. The rear end of the cylinder is closed by a handle 11 having an extension 11a in threaded engagement with the exterior of cylinder 7. The'rear end of cylinder 7 is counterbored at 7 b to provide an enlarged recess in which is disposed a valve case held in place by handle 11, said case comprising interfitting parts 12 and 13 supporting a sleeve valve 14 arranged to control the distribution of the motive fluid and to move automatically in timed relation with piston 8.

Both the valve case 12, 13 and the valve 14 form a part of the piston chamber and receive piston 8 during the reciprocations of the latter. Valve 14: is of simple construction and of three diameters only, namely, a small diameter forward portion 1411, a slightly larger diameter rearward portion 14b, and a substantial centralflangeportion 140. The valve, accordingly, has four pressure areas, namely, the two extreme ends and the two faces of flange 14:0. The valve 14 is shifted to its forward position (Fig. 1) by air trapped and com ressed by the piston during its rearward stro e within a cushion pocket provided by part 1 3 of the valve case. The valve is arranged to bemoved rearwardly initially by pressure fluid admitted from the piston chamber through a port 15a controlled by piston 8 and communicating with the shift passage 15 in the cylinder and thence through a connecting passage 15?; in valve part 12 which opens into valve chamber 16 forward of flange 14c. Cylinder passage 15 is enlarged or counterborcd at 150 to receive an auxiliary valve member which may take the form of a ball 17 adapted to seal passage 15 against reverse movement of pressure fluid there through. When auxiliary valve 17 is in the open position (Fig. 2) pressure fluid is bypassed therearound to valve passage 156 by a ore 15d (Figs. 1, 2, 4 and 6). Part 12 of the valve case engages the shoulder within cylinder 7 provided by counterbore '7) and serves as an abutment or stop for auxiliary valve 17 on its opening movement.

The pressure fluid admitted from piston chamber 764 through port 15a, passage 15, bypass 15d, passage 15?) to valve chamber 16 is intended merely to initiate the rearward movement of the valve, such movement being continued and completed by live pressure fluid which enters through a port 18a uncov ercd by valve flange 1 10, which port communicates with the fluid supply passage 19 in handle 11 by a passage 18 opening into an inclined passage 20. The continuing movement of the valve under the live pressure fluid causes flange 14:0 to uncover one or more ports 21a (Figs. 1, 2 and communicating with elongated passages 21 leading to the extreme forward end of the piston chamber (Fig. 1) to supply motive fluid for driving the piston on its rearward or non-working stroke. As shown diagrammatically in 5, the live air inlet port 18a is formed with a transversely extended opening by slotting the valve case and this slot is arranged to have a pronounced lead over ports 21a when the valve moves rearwardly, thereby to insure early admission of a sufiicient quantity of pressure fluid to chamber 16 to complete the rearward movement of valve 14.

The complete cycle of operation of the hammer is as follows. lVith the parts in the position shown in Fig. 1, the hammer piston i8 is beginning its forward, or working. stroke being driven by live motive fluid from handle inlet 19 which is directed through a series of inclined passages 20 to an inlet groove 20a in the piston chamber, whence it may have access rearwardly of piston S by by-pass 22 when the piston is covering inlet groove 20a as indicated in Fig. 1. Air in advance of piston 8 passes to atmosphere through passages 21, ports 21?), valve chamber 23 rearwarclly of flange 14:0, exhaust ports 2 1a and exhaust passages .21 (Figs. 3 and leading to atmosphere. As piston 8 approaches the end of its stroke it uncovers port 150 and admits fluid from the piston chamber to passage 15 thereby unseati'ng auxiliary valve 17 whence the fluid continues through by-pass 15d and passage 15K to valve chamber 16 and moves the valve rearwardly. The position of the parts is then shown in Figs. 2 and 3. A slight further movement of the va ve promptly uncovers the elongate mouth of live a-i-r .port 18a thereby increasing the pressure in valve chamber 16, which increased pressure forces auxiliary valve 17 back to its sealing position over passage 15 and promptly moves main valve 14 to its rearward position 4). During such movement of main valve 14, piston 8 strikes its blow and recontrol of said pis bounds for the return stroke. The rearward movement of the valve has caused its forward portion 14a to uncover exhaust ports 240 venting the rear end of the piston chamber to atmosphere through passages 24, and flange 140 to uncover ports 21a whereby a portion of the live pressure fluid admitted through port 18a has access through passage 21 to the front end of the piston chamber to drive the piston onits rearward or return 7 stroke. As the piston approaches the rear end of the piston chamber it covers exhaust port 217) and then begins to compress the air trapped within the valve and valve case. The air so trapped and compressed acts againstthe rear end face of the valve and continues to have access thereto through by-pass 22 (Figs. 1 and 2) even after the piston has passed through the valve. The valve then shifts forwardly to the position shown in Fig. 1 and the cycle is complete. A vent 210 of restricted size (Figs. 1, 2 and 5) releases any air trapped in valve chamber 16 after ports 214 are closed by flange 14o.

Fig. 5 illustrates diagrannnatically the relative poition of the various ports in the valve chamber and indicates the position of thevalve after it has begun its rearward movement and reached substantially the position shown in Fig. 2, the four valve areas being indicated by the broken lines cutting icross the diagram. [is indicated the vent orts Qlb for the rear end of the piston chamher are still closed. Live air inlet port 18a by eason. of its slotted month and lead ovrr ports 21a. substantially and for all practh cal. purposes wide open while ports 21a are still closed, or just beginning to be opened. Inlet groove 20a is already closed. This arrangen'ient makes positive the full and prompt movement of main valve 11 to its rearward position. Loss and waste of pressure fluid from valve chamber 16 is obviated by the use of auxiliary valve 17 and the prompt movement of the same to closing position when inlet port 1864 is opened.

lVhile the invention has been herein disclosed in what now considered to be its preferred form, it to be understood that the invention is not limited to the specific details thereof, but covers all changes modifications, and adaptations within the scope of the appended claims.

I claim as my invention:

1. fluid pressure tool comprising a cylin der, a piston reciprocable thereii'i, ports and passages for directing motive fluid into said cylinder to reciprocate said piston, a valve controlling said ports and passages and moving in timed relation with said pis. one oi said vpasages having a port opcnin '1'10111 the piston chamber to admit prei ure fluid under on to move said valve, and an auxiliary valve for preventing reverse movement ot'fiuid in said last-named passage.

2. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, said tool having a valve case and a valve therein for controlling the movement of said piston, a passage extending to a pressure area of said valve and controlled by said piston for admitting pressure fluid from the piston chamber to move said valve, said passage being enlarged adjacent said valve case, and a valve in said enlargement for preventing reverse movement of fluid in said passage, said case serving as a stop for said last-named valve on its opening movement.

3. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, said tool having a valve case and a valve therein for controlling the movement of said piston, a passage extending to a pressure area of said valve and controlled by said piston for admitting pressure fluid from the piston chamber to move said valve, said passage being enlarged adjacent said valve case, and a ball valve in said enlargement for preventing reverse movement of fluid in said passage, said case serving as a stop for said ball valve on its opening movement. 7

4. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, said cylinder having a counterbore, a valve case in said counter-bore having a sleeve valve therein for controlling the movement of said piston, said valve and valve case forming a portion of the piston chamber, a passage provided in the cylinder and valve case under control of said piston for admitting pressure fluid from said piston chamber to a valve chamber to move said valve, said passage having an enlargement adjacent said case, and a valve in said enlargement arranged to abut said case on opening movement but preventing reverse flow of fluid in said passage.

5. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, a valve for controlling the distribution of the motive fluid and moving in timed relation with said piston, means for initiating movement of said valve in one direction comprising a passage having a port controlled by said piston for directing pressure fluid from the piston chamber to a pressure area of said valve, means for continuing the movement of said valve by live pressure fluid comprising a port in connection with the fluid supply arranged to be uncovered by the initial movement of said valve, and a movable member associated with said passage for preventing movement of fluid therethrough from said valve to the piston chamber.

6. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, a valve for controlling the distribution of the motive fluid and moving in timed relation with said piston, means for initiating movement of said valve in one direction comprising a passage controlled by said piston for directing pressure fluid from the'piston chamber to a valve chamber, means for continuing the movement of said valve by live pressure fluid comprising a port connected to the fluid supply arranged to be uncovered by the initial movement of said valve, a passage uncontrolled by said piston for directing fluid from said valve chamberto the piston chamber to effect the non-working stroke of said piston, and means uncontrolled by said valve for preventing movement of pressure fluid from said valve chamber through said piston-controlled passage. v i

7. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, a valve for controlling the distribution of the motive fluid and moving in timed relation with said piston, means for initiating movement of said valve in one direction comprising a passage controlled by said piston for continuing the movement of said valve by live pressure fluid comprising a port connected to the fluid supply arranged to be uncovered by the initial movement of said valve, a passage uncontrolled by said piston for directing fluid from said valve chamber to the piston chamber to eflect the non-working stroke of said piston, and an auxiliary valve arranged to prevent reverse movement of fluid through said piston-controlled passage.

8. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, a valve for controlling the reciprocations of said piston and moving in timed relation with the latter, means for initiating movement of said valve in one direction by pressure fluid from said piston chamber, said tool having a live pressure fluid port uncovered by initial movement of said valve to admit fluid vto a valve chamber, a passage extending from said chamber to convey at least a part of the fluid from said port to drive said piston in one direction, said passage being uncovered subsequent to the uncovering of said port so that the fluid admitted by the latter may be initially eflectiveto complete the movement of said valve.

9. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, a valve forcontrolling the reciprocations of said piston and moving in timed relation with the latter, a flange on said valve providing a pressure area for moving it in one direction, means for admitting pressure fluid to the chamber of said valve area from the piston chamber for initiating movement of said valve, a port communicating with the fluid supply arranged to be uncovered by said valve flange on its initial movement to admit pressure fluid to said valve chamber to complete the movement of the valve, ports also arranged to be uncovered by said valve flange for conducting fluid from said valve chamber to drive said piston in one direction, said fluid supply port having a lead on said last-named ports to" insure full movement of said valve, and a continuously open vent port of restricted size for said valve chamber in communication with one of said last-named ports.

10. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, a valve for controlling the reciprocations of said piston and moving in timed relation With the latter, means for initiating movement of said valve in one dir ction comprising a passage controlled by said piston for admitting pressure fluid from the piston chamber, an auxiliary valve for preventing reverse flow of fluid through said passage, said tool having a live pressure fluid port uncovered by initial movement of said valve to admit fluid to a valve chamber, a passage extending from said chamber to convey at least a part of the fluid from said port to drive said piston in one f direction, said passage being uncovered subsequent to the uncovering of said port so that the fluid admitted by the latter may be initially effective to complete the movement of said valve.

f? 11. A fluid pressure tool comprising a cylinder, a piston reciprocable therein, a valve for controlling the reciprocations of said piston and moving in timed relation with the latter, a flange on said valve providing a f1"; pressure area for mo ing it in one direction,

a passage under control of said piston arranged to admit pressure fluid from the piston chamber to the valve chamber of said valve area for initiating movement of said i 3 Y valve, an auxiliary valve arranged to prevent reverse flow of fluid through said passage, a port communicating with the fluid supply arranged to be uncovered by said valve flange on its initial movement to admit pressure 4.? fluid to said valve chamber to complete the movement of the valve, ports also arranged to be uncovered by said valve flange for conducting fluid from said valve chamber to drive said piston in one direction, said fluid 4.? supply port having a lead on said last-named ports to insure full movement of said valve, and a continuously open vent port of restricted size for said valve chamber in communication with one of said last-named ports.

.7 i Signed by me at Detroit, in the county of Vayne and State of Michigan, this 27 day of September, 1928.

EDlVARD VJ. STEVENS. 

